The present invention relates to a device for transmitting messages in a communication network for voice and data processing of the type having a plurality of terminals which are each allocated to a specific user or can be allocated to a specific user by means of a data carrier insertable in the terminal, at least two terminals being capable of entering into voice or data communication with one another, and having at least one center for controlling the message transmission within the communication network, each message transmission being a data communication wherein data telegrams containing a standardized data header are exchanged.
Many countries currently offer national mobile radio telephone networks using a multitude of technical standards. For international traffic, however, the differing networks constitute an obstacle. A mobile telephone subscriber expects to be able to use his terminal apparatus in various locations in a number of countries, e.g., all over Europe.
With the introduction of the GSM (Global System for Mobile Communication) standard, i.e., the standard for a cellular radio telephone network, the way has become free for a uniform network and thus for international traffic.
FIG. 1 of the accompanying drawings shows the basic structure of a mobile radio telephone network operating according to the GSM standard. Reference numeral 1 therein designates the surface area of the network. This entire area is covered by radio cells 2 adjoining and overlapping one another, only a few such cells being visible in FIG. 1. In each cell 2 there is a base station 3 (Radio Base Station or RBS) which takes care of radio communication to the terminals of the mobile telephone subscribers. Along each radio route between a base station 3 and a terminal 4, all voice and control information, as well as other data such as messages, is transmitted in digitally coded form.
Reference numeral 5 designates a controller (Base Station Controller or BSC) by means of which several base stations are controlled. For example, the controller is responsible for the smooth radio-technical transition of a subscriber, or rather of the terminal allocated to a subscriber, particularly a mobile radio telephone, from one radio cell to an adjacent one. On the basis of automatically performed field strength measurements, the controller decides when the transition should be initiated from one radio cell to which adjacent radio cell. Such a transition is called a handover or handoff.
The controllers are in turn grouped into a higher-ranking mobile radio center 6 (Mobile Service Switching Center or MSC) which establishes the transition to a wired network 7, e.g., an ISDN (Integrated Services Digital Network). In such a telecommunication network, voice information, image information, and information from data-processing equipment, for example, can be transmitted simultaneously.
Reference numeral 9 indicates another terminal, e.g., a personal computer (PC) by means of which, among other things as a data-communication application, messages can be transmitted to a mobile radio telephone 4. The possibility of doing this is known in the art as an SMS (Short Message Service). However, messages may also be transmitted from one mobile radio telephone to another. The connection is then always handled via a so-called Short Message Service Center (SMS-C) 8. The SMS is a telecommunication service which permits messages to be sent from the Short Message Service Center to a GSM subscriber (SMS Mobile Terminated/Point-to-Point or MT/PP) or from a GSM subscriber to the Short Message Service Center (SMS Mobile Originated/Point-to-Point or MO/PP). Each message is then packed in a data telegram preceded by a standardized data header, containing among other things the identification of the subscriber and a code indicating that this is a message.
This procedure, defined in GSM Standard 3.40, is called GSM Phase 2. It allows the transmission of any desired bit streams in a transparent mode. Short messages such as "Please call subscriber XYZ," for instance, can thereby be transmitted from a subscriber A via the Short Message Service Center to a subscriber B. The message is indicated to the recipient in a display, for example.
From GSM Phase 2 there are also so-called Class 2 messages. In mobile radio telephones or other terminals provided for the processing of Class 2 messages, the existence of a storage means is presupposed, preferably a Subscriber Identification Module (SIM) in the form of a chip card. Contained in the storage means are, among other things, all necessary data for identifying the user. Chip cards or processor chip cards can be inserted in any desired terminal to be used. One advantage of such a design is that a mobile radio telephone subscriber, for instance, need not take his own terminal with him but only his chip card.
Class 2 messages or further developments based thereon, which may consist of one or more messages, are filed message-wise in the aforementioned storage means. As soon as this is done, an affirmative acknowledgment is sent to the Short Message Service Center.
The possibility is thereby offered of sending to or receiving from a storage means in a terminal both data and executable instructions.